Ignition device



Patented May 13, 1952 stanley M. Udal; Detroit, Mich; assign'or to George M.- -Holley and .Earl Holley Application January 12, 1949;:seria1N0: 70,529

The objector .thi's inventi'on'is to advance and to" promptly. retardime. spark of an automobile engine. as; circumstances require," specifically to advance-2 (a) when :Tthe .Jsp'e'ed "inerea's'e'sat wider-open throttle;

(b)' }When" thelthro'ttle is only partly" opened and the engine runs .s1ow1y;

(c) :To' retardithe. spark to 'itsnon knocking position very'q'uicklywhen the throttle is opened quickly at low engine speed. (To avoid the'well known acceleration knock.)

Fig.- 1 shows the. preferred form of my inven- I tion.

Fig. 2 :showsthe relationship between speed load' and spark advance.

In the' figures IE1 is the air entrance of a conventionall carburetor l 2. discharging, into" .the venturi IS, in the ajir'Len-' trance vH] of the main ain passage: l'l. (There is a low speedl fuel outlet, not "shown," discharging into the mixture outlet 19 and" discharging ad jacent. the upstream li'p'of thelbutteriiy throttle 32.) [8 is a-passage leading jout'iof the throat of the venturi [6 into a chamber 20; 22 'isth'first" moving wall or diaphragm forming theright hand wall ofchar'rlber 20. 24 is a second; moving wall or diaphragm formingtheright hand wall of chamber 26 which isconn'ected through a pipe28 with an opening '3ll in the'main'fair passage 11," located above the-atmospheric side of the rpm the carburetor'throttle 32 when thecarburetorthrottle 32 is in'itsidle position.

A spark control rod 34' engageswithplate-44 and-is move'd'by two means: 7 t v (a) Directlyby the di"phrajgm-'22 to' which 'itis connected positively," and (bi Indirectly by a sleeve or tube"36surrounding .rod 34.

This sleeve 36 is provided with a short slot*31 so that it can pull the'right hand end'38'of the rod 34 to the leftibut' the rod 34 isfree to be moved to the left by springs '46, 41andplate 44, even though the tube36r'emains in'the position shown. In other words the-"end or therod 34, numbered 38,has a one'way connectioniwhich projects through a slot in the sleeve 36, and engages with the circuit breaker plate 44. 'The tube 36 has arod"extension'40 which is engaged by a compression spring- 42. This springr42 engages at all times with the adjust= ablenut and'washer 43on the threaded rod 40. A stiffer, smaller'and shorter spring4l engages with the washer'43'aftera limited movement ofthe diaphragm 24 to the'left,

The length of the slot 31 is se1ected 'so that" the left hand'end'of the slot 3'lg'whenthethrottle 32 is wide open, engages with the projection 38 of -the rod 34 so as to positively retar'dlthe.

sparkpartially during acceleration when the left;

hand end of the slot 31 engages with the'projection 38.

I4 is the fuel nozzle Thepla-te 44 is-pulled clockwise-by two-springs; 46 and 41, one of which is initially-tight; the other one is loose. These th'r'ee spring's 42-=4B41 control the position ofthe plate :44

at all times. At other times "the" fourth? springs; 4| also is activeto control the advance.. The

reason one oithese two springs 46- -41 -is loose is that one thus tightens up before' the other.'., (See "West'cott et al. case filed December '20;

1946, Serial No. 717,536, now Patent No'.'2,503,64:5, issued April 11, 1950, and 'Colvinet al. case filed September 23, 1948jSerial'No'. 50,796,n0w Patent No. 2,557,527,"issued'June 19, 1951.) The-'pl'ate'i 44 carries a circuit breaker arm 48"which'ene gages with a stationary'contact 49. The cire' cuit'breaker arm '48 is-opened and closedbya. cam 50, a finger 53, andaspring52. Anel'ectri'cali connection 5 4'is provided for the'low tension side of the coil (not shown);

The spring anchor pins 56-51 project thro'ugh circular openings in the circuit breakeritplatel.

44 to provide a maximum but-limited advance of the spark determined by' 'the clearance" oilLthei' pins 56 and 51 in these'op'ehings.

Operation- The throttle 32 is shown in' four"po's'itions".-

Position #1 (idle) is shown in full'line,"p osition #2 is shown during normal city drivingiposition #3 is wide open and position .#4is during normal country'driving with the throttle almost wide open.

When moving from position 1 to position'2 the" sparktrave'ls from A to'F without'much' ad- Vance and then rises 'very rapidly to'point G which' is" the maximum advance permitted by ADE. As the speed increases the depression in'pipe I8 increases so that both dia'ph'ragmscontribute to the advance. When the throttle is opened Wide the suction in pipe 28'falls be lowthat which'can' overcome the spring 42" and the only. force advancing the spark is theVenturi suction transmitted through the pipe l8"- to* act onlthe diaphragm" 22; The-diaphragm 24 is" then" in theflposition shown, that is,' in itsextreme position over to theri'ght when'it is inoperat-iveto advance the spark.

The slot 31 is ofsuch a-=length 'that when accelerating by opening thethrottle wide open' the spark is positively knocked down from tlie' horizontal line G to the horizontal line through- Cithatis, rromap m 25.

' The "curve from idletc ordiha'r'ywoadload is'the normal sparkadvance. ABCisthe' normalspark for *wide open throttle -(-position- #3) operation and a curve such as ADE is an intermediate sparkadvance curve when the throttle is not quite wide open (position #4) The slight inflection in the line ABC at point B, (800 R. P. M.) and in the line ADE at point D is caused by the springs 46 and 41 as set forth in the copending applications, Serial #717,536 Westcott et a1. and Serial #501796 Colvin et al.

The modification covered by these applications is the fact that one of the two springs 46 and 41 is loose so that the line AB rises at a more rapid rate than the line BC. If only one spring were used the inflection in the lines ABC and ADE would be reversed.

Theymodifications of this application are:

(a) The substitution of a short stiff inner spring 4! and a more flexible outerspring 42 for the single stiff spring of Serial #50,7 96.

(b) The short length of the slot 31 so that .during acceleration the springs 4| and 42 positively knock the spark down to avoid making the engine knock.

If only one spring replaced the two springs 4! and 42 then when the throttle moved from its wide open position #3 to position #4 then the suction in Venturi l6 would fall and the spark advance curve would fall below the line ABEC but the line ABEC is the lowest spark advance for good fuel economy.

Actually when the throttle moves from wide open to position #4 the spark should be advanced slightly (ADE). The smaller the engine the more important does this feature become, as the smaller engine operates more frequently with the throttle almost wide open then larger engines which operate either with the throttle open or closed. Dynamic suction describes the suction applied to the first moving wall 22. Static suction describes the suction applied to the second moving wall 24.

What I claim is:

l. Aninternal combustion engine ignition system comprising a main air passage for said engine, an air entrance thereto, a streamlined restriction in said entrance, an air outlet passage, a throttle valve therein, a first chamber, .a first moving wall therein, a passage from said first chamber to the air entrance at the throat of said restriction, a second chamber, a second moving wall therein, a second passage from the air outlet passage at a point in said outlet where, when the throttle is closed, the passage is in communication with atmospheric pressure and as the throttle is opened it is gradually transferred to the suction on the engine side of said throttle, a spark timing advance plate, a circuit breaker mechanism mounted therein, two springs connected to said plate at one end, two fixed anchors connected to the other ends of said springs so that said springs oppose the movement of said'plate in the spark advancing direction, one of said springs being made initially active to oppose the spark advance, the other having clearance so as to become active immediately after the plate begins to move away from its retarded position, a first rod connecting the first moving Wall to said plate, a second rodconnecting the second moving wall to said first rod through a one way connection, a third spring engaging with the second rod after the second rod has been moved by the two moving walls, a predetermined limited movement away from the extreme retarded position, a fourth control spring arranged to engage with said second rod when said second rod is in its extreme-spark retarded position, said fourth control spring being relatively much Weaker than said third control 1 spring. I

, 2. A device as set forth in claim 1 in which one end of the second rod is slotted to permit one end of the first rod to project through said slot to engage said plate so as to form said one way connection, said second rod is engaged by said fourth and third control springs and the slot is of such a length that when the throttle is suddenly opened wide during acceleration the escape of suction in the second chamber causes the second moving wall and the second control rodto move under the influence of the fourth and third control springs and to positively engage the first rod and to retard the spark by the "impact of the second moving wall and second on a movable plate the movement of which is p responsive to the dynamic suction created by the air fiow through said Venturi and to the static suction created downstream of said throttle whenever the throttle is moved from its wide open position, the improvement which consists of .a first chamber, a first moving wall therein, a passage from said first chamber to the Venturi, a second chamber, a second moving wall therein, a second I passage from the second chamber to a point that is transferred from the engine side of the throttle to the atmospheric side whenever the throttle approaches its closed position, a first link from the first moving 'wall to said movable plate, first yieldable means tending to rotate the plate in opposition to said dynamic suction, a second rod connected to said second moving wall, second 7 yieldable means opposing the movement of said second moving wall in response to saidstatic suction, said means being initially sufficiently weak to respond to the weak suction created by the initial closing motion of the throttle from its wide open position, a loose connection between the first and second rods to permit the.

first rod to act alone and to permit the second rod to assist the first rod to advance the timing whenever the static suction created by the initial movement of the throttle away from its wide I open position becomes appreciable.

4. A device as set forthin claim 3 in which i the second yieldable means comprises a variable v yieldable means in which the initial resistance of said second yieldable means to static suction is relatively weak and after a relatively small movement of said second moving wall from its idle position, a relatively stiff yieldable means opposes the further movement of said second moving wall.

STANLEY M. UDALE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 7 Number Name Date 1,845,818 Spiller Feb. 16, 1932 Harmon Aug. 31, 19:37 

